Apparatus for testing altimetric devices



June 24, 1947 c. H. H. RODANET APPARATUS FOR TESTING ALTIMETRIC DEVICES Filed Oct. 22, 1940 INVE'NTOR CHARLES HILAIRE HENRI RODANET \BY I M ,mgg. ATTORNEYJ Patented June 24, 1947 DEVICES Charles Hilaire Henri Roaanet, Neuflfwsnr-Seine,

France; vested the Uhifeil States Attorney General of tire Application (jctober 22, 1940, Serialr lfo V In France September 1, 1939 by means of which the speed. for automatically obtaining said partial vacuum and for re -estab lishing.atmo'sphericpresslne is adjustable at will. Finally, it includes all applications of Said; device oeiaiims. (Cl. 13am and of its improvement; however, the invention I is more particularly applied tothe" control of the graduation of altimetric, manometri'c' and like apparatus.

In its construction, the device is mainly characterised by the fact-that the closed chamber or enclosure" is connected to a cook or the like, arranged to" put said enclosurein communication either with the atmosphere, or with a source of partial vacuum, according to its position, said cock being electrically controlled by a circuit comprising a first adjusting switch, actuated by hand, and a second "switch automatically actuated by a' standard pressure-gauge which measures the pressure in the'eiicl'osure. I

Functionally, the device is characterised by the fact that when the pressure in the enclosure exseats? the value'corresponding to the position initially given to the hand adjusting swi'tch, the control circuit is in such condition that the cock puts the enclosure in communication with the sourceof artial vacuum: whereas", whenthe pressure in the enclosure bec'oih'es lower than the acfjust'ed value, the manometr'ic switch changes the condition of the control circuit so that the cock" puts the encrosure in communication with the atmosphere. h

The'cie'vic'e' can of course have several forms of construction, in which the controlcir'cuit'l's closed when the-pressure inthe enclosure exceeo the value corresponding to the position initially iven-to the hand adjustin switch, and the osition of the cock out-ting the enclosure in cornniun-i'c'a-t-ien with the source of partial vacuum, corresponds to the excitation of the control circuit.

It will? be seen that the apparatus comprises means adapted to place the contact position of automatic switch the control of that oi the adjusting? switch; new; numerous control means or this kind: are known; and: it can be said, in thatsense; that the invention is characterised by the new apfilication oi those known means to the control-oi a; manometrio' switch, order to obtain new industrial results; particularly when the device is used for controlling the graduation otaltimetric; ma nom'etno' or like appa'ratns'.v

control or altiinetric apparatus i usuall eiiectedby arranging the utter under a vacuum boil in a pressure is created correspondin to ,fihat of the various altitudes at winch the norcation supplied is to be controlled. This bell is usualiy communication with the atmosphere and a vacuum oufii by means of conduits pro: vided cook's. These cocks are actuated by hand until a st'e'andfar i oriessufe-gauge connected to the bell indicates the desired value. v 7

new, ex erience has shown that it is extrenieiy lon and laborious to obtain these exact pressures Within 011 Ill. Iii, Wfiefi the operation 15 fp fd many times, owing to the oscillations of the inerclh? cdllifiiiimid to the slowness" with which it oomesto .eqifilibriuin, then, oWi-fig to the fact that the changes of ressure .01 the air in the hell determine variations of temperature, eq'uflihfiiiin with the surrounding medium is onto r-es'taibl'ished slowly. Finally; notwithstanding. an the care taken, anerror always sobsists, called; the personal equation. 7

The invention allows of obtaining automaticalIy, exactly, and in the mini-mum time, any desired pressure in the vacuum hell.

The device generally characterised alcove can be constructed according to various forms, all included in the invention, and which candifi'er from each other, in particular, hy'the' nature of the cock-, of the source of par-tial vacuum, of the hand adjusting switch, of the automatic switch, of the electric Wiring putting said second switch under the control of the first one, of the standardpressure-gauge actuating the automatic switch, etc. It is obvious that of these various members can be any one of used, iirthe art and not only those -whi'ch will be described hereinatter in a particular formpf construction of the invention taken by way of; example The improvement as means oi which it is; possibleto ad just at will the speedwith the desired partial vacuumis obtained and the speed which atmospheric oressu r is re-establisheu, is characterised, its co struction, by a,

normally open contact which when it isclosed, shunts both: switches ofthe control circuito by a normally closedcontact arranged in series: on the control circuit; andby anadiiustable leakage variometer' control-ling said contacts. 7

Functionally, saidgimprovement is characterised by the fact that it the speed for obtaining-the partiai vacuum is-;too;great,-.the variometer opens the normally closed contact, which" cuts off: the control circuit and ,actnates-rthe cock the di feotion tor throttling the suction or the source The three main elements of the preferred form of construction of the device, illustrated by way of example in the accompanyingdrawing, are constituted:

(1) By a mercury barometric pressure-gauge the vertical tube of which is preferably made of insulating material and provided with metal members which are contacted by the mercury column.

(2) By an adjustable variometer controlling one or more electric contacts (3) By one or more air cocks controlled by the contacts of the barometric'column or those of the variometer or both simultaneously. An electric switch allows of choosing the altitude at which the pressure in the bell is to be adapted, whilst a cock combined with the variometer allows of adjusting the upward or downward speed.

The operation for opening and closing the cock or cocks can be controlled by any suitable means such as an electromagnet, but preferably, by the expansion of a heated wire, the effect being more gradual.

The accompanying drawing illustrates the general diagram of the apparatus. Reference number I designates the mercury barometer having contacts; 2 the altitude switch, adjustable by hand; '3 a three-way cock controlled by the heated wire 4. The variometer 5 is composed of two capsules 6 and I, an undistortable vessel 8 and a progressive cock 9; the variometer controls the contacts I0 and II. The vat of the barometric pressure-gauge I is connected, on the one hand, to the cock 3 and, on the other hand, to the vacuum bell I2 connected in its turn to the variometer and'to a control pressure-gauge I3, on which the actualpressure can be read. The

,Vat of the barometricpressure-gauge I has a contact which is connected to one of the poles of a source of current I9; the circuit closes through the mercury contacts, switch 2, expansible wire 4 and reaches the other pole through the normally closed contact II]. The wire 4 can also be supplied with current through the normally open contact II.

The operation is as follows:

When the switch 2 is on the dead contactpiece I 4, the electric circuit is cut off, the wire 4 is cold and the cock 3 open to the atmosphere at H. The switch 2 being shifted to the contactpiece corresponding, for instance, to an altitude of 3000 meters, the current passes through the wire 4, which expands, and the cock 3 opens to a vacuum pump (not shown) connected at I6. Suction takes place in the vat of the pressure-gauge I andin the vacuum bell I2 until the mercury column of pressure-gauge I reaches below the level of the contact-piece corresponding to 3000 meters, and cuts off the current. The wire t cools, actuates the cock which again tends to cause the pressure to increase.

Finally, equilibrium is obtained and the current passes intermittently through wire 4, heating it moderately, which maintains the cock or valve 3 closed. The pressure remains stable in the bell 4 I2. It will be noted that said pressure is automatically fixed when going up or down, according to the contact-piece chosen for contact by the switch 2. The rate of change in the variation of pressure within the bell I2 is controlled by the cock 9 of the variometer. Thus, if the air within the bell is being withdrawn at a rate greater than that fixed by the variometer, the lever I8 will open the contact II], this having the effect of cooling the wire 4 and of reducing the extent of opening of the-cock 3 to the vacuum pump. If the rate of air admission to the bell is too great,

1 the variometer will close the contact II, wire 4 is supplied with current and reduces the extent of opening of cock 3 to the atmosphere. It will be noted that the rate of air flow controls fixed by the cook or valve 9 are independent of the volume of the bell I2.

What I claim as my invention and desire to secure by Letters Patent is:

1. Automatic apparatus for producing and maintaining a predetermined partial vacuum within a hollow container or enclosed member for testing altimetric devices, said apparatus including the hollow container for receiving such devices, a, valve having a casing connected with the interior of said container and containing a movable valve member which in one position in said casing places said container in communication with a passageway adapted to be connected with a suction means andin another position places the container in communication with the atmosphere, a pressure gauge communicating with the interior of said container for measuring the pressure within the latter, anelectric control circuit fed by a current source, electric shifting means in said circuit for moving said valve member upon closure of the circuit, a switch in said circuit operable by a. movable portion of said pressuregauge for controlling the position of said shifting means, and including a manual adjusting switch member for predetermining the desired pressure in said container. 7 2. Automatic'apparatus' according to claim 1, having the switch of the control circuit closed when pressure prevails in the container in excess .of that corresponding to the adjusted position of the 'manual adjusting switch member and the simultaneous .position of the valve member in the valve casing placing the container in communication with the passageway adapted to be connected with suction means corresponds to closed operating condition of the control circuit.

3. Automatic apparatus according to claim 1, having a switch for controlling the rate of pressure variation in said container comprising a pair of normally closed contacts in series with the circuit, a pair of normally open contacts arranged in a shunt branch circuit shunting both the manual adjusting switch and said pair of normally closed contacts when said normally open contacts are in closed positions, and means responsive to a predetermined pressure condition within said container for actuating the normally open contacts to thereby close the shunt branch circuit.

4. Automatic apparatus according to claim 1 having a switch for-controlling the rate of pressure Variation in said container comprising a pair of normally closed contacts in series with the circuit and a pair of normally open contacts tainer, and a movable lever operated by said pressure responsive member in response to rate of change variations and arranged to open the normally closed contacts in one position and to close the normally open contacts in another position.

5. Automatic apparatus according to claim 1 having a switch for controlling the rate of pressure variation in said container comprising a, pair of normally closed contacts in series with the circuit and a pair of normally open contacts arranged in a shunt branch circuit shunting both the manual adjusting switch and said pair of normally closed contacts when said normally open contacts are in closed positions, two pressure responsive members connected to each other by a conduit and in communication with the container, a movable lever operated by said pressure responsive members in response to rate of change variations and arranged to open the normally closed contacts in one position and to close the normally open contacts in another position, and a manually adjustable leak valve in the conduit between the pressure responsive members controlling the passage of pressure fluid from one to the other.

CHARLES HILAIRE HENRI RODANET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

